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Old 2014-08-01, 17:24   #6
Batalov's Avatar
Mar 2008

59×157 Posts

When I first looked at the factordb entry it still had a c650 cofactor. But I recently was ruminating about x^y+y^x and convinced myself that x=4 would be a "Sierpinski-like number" for it because the expression was never prime (y>1), algebraically. Well, it is not a "Sierpinski-like number" in spirit, really; there is no covering set.

So, I submitted the
factors; the DB usually does gcd, but it didn't. Then I ran gcd in Pari and submitted the c245 and c405, and the entry started to look like it does now.

For fun, I've done the same to
Of course, one can also generate a test file of these algebraic factorizations with awk or perl and submit it to the DB...
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